U.S. patent application number 11/677599 was filed with the patent office on 2008-08-28 for radiation-sensitive compositions and elements with basic development enhancers.
Invention is credited to Tanya Kurtser, Moshe Levanon, Larisa Postel, Marina Rubin.
Application Number | 20080206678 11/677599 |
Document ID | / |
Family ID | 39485075 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080206678 |
Kind Code |
A1 |
Levanon; Moshe ; et
al. |
August 28, 2008 |
RADIATION-SENSITIVE COMPOSITIONS AND ELEMENTS WITH BASIC
DEVELOPMENT ENHANCERS
Abstract
Radiation-sensitive compositions can be used to prepare
positive-working imageable elements useful for example to make
lithographic printing plates. The compositions include an aqueous
alkaline solvent soluble polymeric binder that includes a phenolic
resin (such as a novolak) or a poly(vinyl acetal). The compositions
also include a developability-enhancing composition comprising one
or more basic nitrogen-containing organic compounds. The
radiation-sensitive composition can be coated as an imageable layer
that further includes a radiation absorbing compound that is, for
example, sensitive to infrared radiation.
Inventors: |
Levanon; Moshe; (Ness-Ziona,
IL) ; Postel; Larisa; (Ashdod, IL) ; Rubin;
Marina; (Petah-Tikva, IL) ; Kurtser; Tanya;
(Petach Tiqwa, IL) |
Correspondence
Address: |
Andrew J. Anderson;Patent Legal Staff
Eastman Kodak Company, 343 State Street
Rochester
NY
14650-2201
US
|
Family ID: |
39485075 |
Appl. No.: |
11/677599 |
Filed: |
February 22, 2007 |
Current U.S.
Class: |
430/286.1 ;
430/270.1 |
Current CPC
Class: |
Y10S 430/121 20130101;
B41C 2210/02 20130101; B41C 2210/24 20130101; B41M 5/368 20130101;
B41C 2210/262 20130101; B41C 1/1008 20130101; B41C 2210/06
20130101; B41C 2210/22 20130101; Y10S 430/12 20130101 |
Class at
Publication: |
430/286.1 ;
430/270.1 |
International
Class: |
G03C 1/00 20060101
G03C001/00 |
Claims
1. A radiation-sensitive composition comprising: a. an aqueous
alkaline developer soluble polymeric binder that comprises a
poly(vinyl acetal), and b. a developability-enhancing composition
comprising a basic nitrogen-containing organic compound, wherein
said developability-enhancing composition comprises one or more
basic nitrogen-containing compounds that are represented by the
following Structure (II):
(R.sub.7).sub.s--N--[(CR.sup.8R.sup.9).sub.t--OH].sub.v (II)
wherein s is 0,1, or 2 and v is to 1 to 3, provided that the sum of
s and v is 3, and t is 1 to 6, and when s is 1,R.sup.7 is hydrogen
or an alkyl, alkylamine, cycloalkyl, heterocycloalkyl, aryl,
arylamine, or heteroaryl group, and when s is 2, the multiple
R.sup.7 groups can be the same or different alkyl, alkylamine,
cycloalkyl, heterocycloalkyl, aryl, arylamine, or heteroaryl
groups, or the two R.sup.7 groups together with the nitrogen atom,
can form a substituted or unsubstituted heterocyclic ring, and
R.sup.8and R.sup.9 are independently hydrogen or an alkyl
group.
2. The radiation-sensitive composition of claim 1 further
comprising a radiation absorbing compound.
3. (canceled)
4. The radiation-sensitive composition of claim 1 wherein said
polymeric binder comprises a poly(vinyl acetal) that has from about
50 to about 75 mol % recurring acetal-containing units.
5. The radiation-sensitive composition of claim 1 wherein said
polymeric binder comprises a poly(vinyl acetal) that comprises
recurring units represented by the following Structure (PVAc):
##STR00011## wherein R and R' are independently hydrogen or an
alkyl or halo group, and R.sup.2is a substituted or unsubstituted
phenol, naphthol, or anthracenol group.
6. The radiation-sensitive composition of claim 4 wherein said
polymeric binder comprises a poly(vinyl acetal) that is represented
by the following Structure (I):
--(A).sub.m--(B).sub.n--(C).sub.p--(D).sub.q--(E).sub.r-- (I)
wherein: A represents recurring units represented by the following
Structure (Ia): ##STR00012## B represents recurring units
represented by the following Structure (Ib): ##STR00013## C
represents recurring units represented by the following Structure
(Ic): ##STR00014## D represents recurring units represented by the
following Structure (Id): ##STR00015## E represents recurring units
represented by the following Structure (Ie): ##STR00016## m is from
about 5 to about 40 mol %, n is from about 10 to about 60 mol %, p
is from 0 to about 20 mol %, q is from about 1 to about 20 mol %
and r is from about 5 to about 60 mol %, provided that m+n+p is at
least 50 mol %, R and R' are independently hydrogen or an alkyl or
halo group, R.sup.1 is an alkyl, cycloalkyl, or aryl group other
than a phenol or naphthol, R.sup.2 is a phenol or naphthol group,
R.sup.3 an alkyl group, R.sup.4is an --O--C(=O)--R.sup.5 group
wherein R.sup.5 is an alkyl or aryl group, and R.sup.6 is a hydroxy
group.
7. The radiation-sensitive composition of claim 6 wherein m is from
about 15 to about 35 mol %, n is from about 20 to about 40 mol %, p
is from 0 to about 10 mol %, q is from about 1 to about 15 mol %, r
is from about 15 to about 55 mol %, and s is from about 5 to about
15 mol %.
8. (canceled)
9. The radiation-sensitive composition of claim 1 wherein t is 2
and R.sup.8 and R.sup.9 are both hydrogen.
10. The radiation-sensitive composition of claim 1 wherein said
developability-enhancing composition comprises one or more of
N-(2-hydroxyethyl)-2-pyrrolidone, 1 -(2-bydroxyethyl)piperazine,
N-phenyldiethanolamine, triethanolamine,
2-[bis(2-hydroxyethyl)amino]-2-hydroxyethyl- 1.3 -propanediol,
N,N,N',N'-tetrakis(2-hydroxyethyl)-ethylenediamine,
N,N,N',N'-tetrakis(2-hydroxypropyl)-ethylenediamine, 3
-[(2-hydroxyethyl)phenylamino] propionitrile, and hexahydro-
1,3,5-tris(2-hydroxyethyl)-s-triazine.
11. The radiation-sensitive composition of claim 1 wherein said one
or more basic nitrogen-containing organic compounds are present in
an amount of from about 1 to about 30% of the total
radiation-sensitive composition solids.
12. The radiation-sensitive composition of claim 1 comprising two
or more of said basic nitrogen-containing organic compounds.
13. The radiation-sensitive composition of claim 1 comprising one
or more of said basic nitrogen-containing organic compounds and one
or more acidic developability-enhancing compounds.
14. The radiation-sensitive composition of claim 1 wherein said
basic nitrogen-containing organic compound is a liquid at
25.degree. C., or it has a boiling point greater than 300.degree.
C. and an evaporation rate <0.01 relative to n-butyl
acetate.
15. A positive-working imageable element comprising a substrate,
and having thereon: an imageable layer comprising an aqueous
alkaline developer soluble polymeric binder that comprises a
poly(vinyl acetal), a developability-enhancing composition
comprising a basic nitrogen-containing compound, and a radiation
absorbing compound, wherein said developability-enhancing
composition comprises one or more basic nitrogen-containing
compounds that are represented by the following Structure (II):
(R.sup.7).sub.s--N--[(CR.sup.8R.sup.9).sub.t--OH].sub.y (II)
wherein s is 0,1, or 2 and v is 1 to 3, provided that the sum of s
and v is 3, and t is 1 to 6, and when s is 1, R.sup.7 is hydrogen
or an alkyl, alkylamine, cycloalkyl, heterocycloalkyl, aryl,
arylamine, or heteroaryl group, and when s is 2, the multiple
R.sup.7 groups can be the same or different alkyl, alkylamine,
cycloalkyl. heterocycloalkyl, aryl, arylamine, or heteroaryl
groups, or the two R.sup.7 groups together with the nitrogen atom,
can form a substituted or unsubstituted heterocyclic ring, and
R.sup.8 and R.sup.9 are independently hydrogen or an alkyl
group.
16. The element of claim 15 wherein said polymeric binder is
present at a coverage of from about 30 to about 95 weight %, said
developability-enhancing composition is present at a coverage of
from about 1 to about 30 weight %, and said radiation absorbing
compound is an infrared radiation absorbing compound that is
present at a coverage of from about 0.1 to about 20 weight %, all
based on the total dry weight of said imageable layer.
17. (canceled)
18. The element of claim 15 wherein said polymeric binder comprises
a poly(vinyl acetal) that comprises recurring units represented by
the following Structure (PVAc): ##STR00017## wherein R and R' are
independently hydrogen or an alkyl or halo group, and R.sup.2is a
substituted or unsubstituted phenol, naphthol, or anthracenol
group.
19. The element of claim 15 wherein said polymeric binder comprises
a poly(vinyl acetal) that is represented by the following Structure
(I): --(A).sub.m13 (B).sub.n--(C).sub.p--(D).sub.q--(E).sub.r-- (I)
wherein: A represents recurring units represented by the following
Structure (Ia): ##STR00018## B represents recurring units
represented by the following Structure (Ib): ##STR00019## C
represents recurring units represented by the following Structure
(Ic): ##STR00020## D represents recurring units represented by the
following Structure (Id): ##STR00021## E represents recurring units
represented by the following Structure (Ie): ##STR00022## m is from
about 5 to about 40 mol %, n is from about 10 to about 60 mol %, p
is from 0 to about 20 mol %, q is from about 1 to about 20 mol %,
and r is from about 5 to about 60 mol %, provided that m+n+p is at
least 50 mol %, R and R' are independently hydrogen or an alkyl or
halo group, R.sup.1 is an alkyl, cycloalkyl, or aryl group other
than a phenol or naphthol, R.sup.2 is a phenol or naphthol group,
R.sup.3 is an alkyl group, R.sup.4is an --O--C(=O)--R.sup.5 group
wherein R.sup.5 an alkyl or aryl group, and R.sup.6 is a hydroxy
group.
20. (canceled)
21. The element of claim 19 wherein t is 2 and R.sup.8 and R.sup.9
are both hydrogen.
22. The element of claim 15 wherein said developability-enhancing
composition comprises one or more of
N-(2-hydroxyethyl)-2-pyrrolidone, 1 -(2-hydroxyethyl)piperazine,
N-phenyldiethanolamine, triethanolamine,
2-[bis(2-hydroxyethyl)amino]-2-hydroxymethyl- 1.3-propanediol,
N,N,N',N'-tetrakis(2-hydroxyethyl)-ethylenediamine,
N,N,N',N'-tetrakis(2-hydroxypropyl)-ethylenediamine, 3
-[(2-hydroxyethyl)phenylamino]propionitrile, and hexahydro-
1,3,5-tris(2-hydroxyethyl)-s-triazine.
23. The element of claim 15 wherein said basic nitrogen-containing
organic compound is a liquid at 25.degree. C., or it has a boiling
point greater than 300.degree. C. and an evaporation rate <0.01
relative to n-butyl acetate.
24. The element of claim 15 wherein said developability-enhancing
composition comprises one or more of
N-(2-hydroxyethyl)-2-pyrrolidone, triethanolamine, and
N,N,N',N'-tetrakis(2-hydroxypropyl)-ethylenediamine, in an amount
of from about 3 to about 15 weight % based on the total dry weight
of said imageable layer.
25. A method of making a printing plate comprising: A) imagewise
exposing the positive-working imageable element of claim 15 to
provide exposed and non-exposed regions, and B) developing said
imagewise exposed element to remove only said exposed regions.
26. The method of claim 25 wherein said imageable element is imaged
at a wavelength of from about 700 to about 1200 nm.
27. The method of claim 25 wherein said imageable element comprises
a polymeric binder in said imageable layer that comprises a
poly(vinyl acetal) that comprises recurring units represented by
the following Structure (PVAc): ##STR00023## wherein R and R' are
independently hydrogen or an alkyl or halo group, and R.sup.2 is a
substituted or unsubstituted phenol, naphthol, or anthracenol
group, and said developability-enhancing composition comprises one
or more basic nitrogen-containing organic compounds that we
represented by the following Structure (II):
(R.sup.7).sub.s--N--[(CR.sup.8R.sup.9).sub.t--OH].sub.v (II)
wherein s is 0,1,or 2 and v is 1 to 3, provided that the sum of s
and v is 3, and t is 1 to 6, and when s is 1, R.sup.7 is hydrogen
or an alkyl, alkylamine, cycloalkyl, heterocycloalkyl, aryl,
arylamine, or heteroaryl group, and when s is 2, the multiple
R.sup.7 groups can be the same or different alkyl, alkylamine,
cycloalkyl, heterocycloalkyl, aryl, arylamine, or heteroaryl
groups, or the two R.sup.7 groups together with the nitrogen atom,
can form a substituted or unsubstituted heterocyclic ring, and
R.sup.8 R.sup.9 are independently hydrogen or an alkyl group.
Description
FIELD OF THE INVENTION
[0001] This invention relates to radiation-sensitive compositions
and positive-working imageable elements prepared using these
compositions. It also relates to methods of imaging these elements
to provide imaged elements that can be used as lithographic
printing plates.
BACKGROUND OF THE INVENTION
[0002] In lithographic printing, ink receptive regions, known as
image areas, are generated on a hydrophilic surface. When the
surface is moistened with water and ink is applied, the hydrophilic
regions retain the water and repel the ink, the ink receptive
regions accept the ink and repel the water. The ink is then
transferred to the surface of suitable materials upon which the
image is to be reproduced. In some instances, the ink can be first
transferred to an intermediate blanket that in turn is used to
transfer the ink to the surface of the materials upon which the
image is to be reproduced.
[0003] Imageable elements useful to prepare lithographic (or
offset) printing plates typically comprise one or more imageable
layers applied over a hydrophilic surface of a substrate (or
intermediate layers). The imageable layer(s) can comprise one or
more radiation-sensitive components dispersed within a suitable
binder. Following imaging, either the exposed regions or the
non-exposed regions of the imageable layer(s) are removed by a
suitable developer, revealing the underlying hydrophilic surface of
the substrate. If the exposed regions are removed, the element is
considered as positive-working. Conversely, if the non-exposed
regions are removed, the element is considered as negative-working.
In each instance, the regions of the imageable layer(s) that remain
are ink-receptive, and the regions of the hydrophilic surface
revealed by the developing process accept water or aqueous
solutions (typically a fountain solution), and repel ink.
[0004] Similarly, positive-working compositions can be used to form
resist patterns in printed circuit board (PCB) production,
thick-and-thin film circuits, resistors, capacitors, and inductors,
multichip devices, integrated circuits, and active semiconductive
devices.
[0005] "Laser direct imaging" methods (LDI) have been known that
directly form an offset printing plate or printing circuit board
using digital data from a computer, and provide numerous advantages
over the previous processes using masking photographic films. There
has been considerable development in this field from more efficient
lasers, improved imageable compositions and components thereof.
[0006] Thermally sensitive imageable elements can be classified as
those that undergo chemical transformation(s) in response to,
exposure to, or adsorption of, suitable amounts of thermal energy.
The nature of thermally induced chemical transformation may be to
ablate the imageable composition in the element, or to change its
solubility in a particular developer, or to change the tackiness or
hydrophilicity or hydrophobicity of the surface layer of the
thermally sensitive layer. As such, thermal imaging can be used to
expose predetermined regions of an imageable layer that can serve
as a lithographic printing surface or resist pattern in PCB
production.
[0007] Positive-working imageable compositions containing novolak
or other phenolic polymeric binders and diazoquinone imaging
components have been prevalent in the lithographic printing plate
and photoresist industries for many years. Imageable compositions
based on various phenolic resins and infrared radiation absorbing
compounds are also well known.
[0008] A wide range of thermally-imageable compositions useful as
thermographic recording materials are described in GB Patent
Publication 1,245,924 (Brinckman). This publication describes
increasing the solubility of any given area of the imageable layer
in a given solvent by heating the imageable layer by indirect
exposure to a short-duration, high intensity visible light or
infrared radiation. This radiation can be transmitted or reflected
from the background areas of a graphic original located in contact
with the recording material. The publication describes various
mechanisms and developing materials and novolak resins are included
among the aqueous developable compositions that can also include
radiation absorbing compounds such as carbon black or C.I. Pigment
Blue 27.
[0009] Other thermally imageable, single- or multi-layer elements
are described for example, in WO 97/039894 (Hoare et al.), WO
98/042507 (West et al.), WO 99/011458 (Ngueng et al.), U.S. Pat.
Nos. 5,840,467 (Katatani), 6,060,217 (Ngueng et al.), 6,060,218
(Van Damme et al.), 6,110,646 (Urano et al.), 6,117,623 (Kawauchi),
6,143,464 (Kawauchi), 6,294,311 (Shimazu et al.), 6,352,812
(Shimazu et al.), 6,593,055 (Shimazu et al.), 6,352,811 (Patel et
al.), 6,358,669 (Savariar-Hauck et al.), and 6,528,228
(Savariar-Hauck et al.), U.S. Patent Application Publications
2002/0081522 (Miyake et al.) and 2004/0067432 A1 (Kitson et
al.).
PROBLEM TO BE SOLVED
[0010] The industry has focused on the need to diminish the
solubility of the exposed regions of phenolic binders (dissolution
inhibitors) in the imageable layers before exposure and to enhance
their solubility after exposure to suitable thermal energy
(dissolution enhancers). Several materials capable of increasing
the sensitivity of positive-working compositions have been
described. All of the described previous dissolution enhancers are
of an acidic nature, and include sulfonic acids, sulfinic acids,
alkylsulfuric acids, phosphonic acids, phosphinic acids, phosphoric
acid esters, carboxylic acids, phenols, sulfonamides and
sulfonimides.
[0011] These organic acids and cyclic acid anhydrides may be used
alone, but they are preferably used in any combination of at least
two of them. It is also preferable to use at least one cyclic acid
anhydride in addition to at least two organic acids since such a
combination would permit the achievement or further improved
developing latitude and printing durability.
[0012] WO 2004/081662 (Memetea et al.) describes the use of various
developability-enhancing compounds of acidic nature with phenolic
polymers or poly(vinyl acetals) to enhance the sensitivity of
positive-working compositions and elements so that required imaging
energy is reduced. Some of the particularly useful poly(vinyl
acetals) for such compositions and elements are described in U.S.
Pat. Nos. 6,255,033 (Levanon et al.) and 6,541,181 (Levanon et
al.).
[0013] While the compositions described in the noted Memetea and
Levanon et al. publications have provided important advances in the
art, there is a continuing need to improve the sensitivity of
positive-working compositions and elements even more, and
particular in response to infrared radiation.
SUMMARY OF THE INVENTION
[0014] The present invention solves the noted problem with a novel
composition and positive-working element. Thus, the present
invention provides a radiation-sensitive composition
comprising:
[0015] a. an aqueous alkaline developer soluble polymeric binder
that comprises a phenolic resin or a poly(vinyl acetal), and
[0016] b. a developability-enhancing material comprising a basic
nitrogen-containing organic compound.
[0017] This invention also provides a positive-working imageable
element comprising a substrate and having thereon an imageable
layer comprising an aqueous alkaline developer soluble polymeric
binder that comprises a phenolic resin or a poly(vinyl acetal), a
developability-enhancing material comprising a basic
nitrogen-containing organic compound, and a radiation absorbing
compound.
[0018] Further, this invention provides a method of making a
printing plate comprising:
[0019] A) imagewise exposing the positive-working imageable element
of this invention to provide exposed and non-exposed regions,
and
[0020] B) developing the imagewise exposed element to remove only
the exposed regions.
[0021] The positive-working compositions and imageable elements of
this invention exhibit improved sensitivity to imaging radiation.
In addition, it was found that the imageable elements of this
invention provide extremely good press performance when not baked
after development. However, when they are baked after development,
they provide extremely long run length in presence of any
aggressive press chemicals.
[0022] These advantages have been achieved by using a
developability-enhancing composition containing a particular class
of basic nitrogen-containing organic compounds in combination with
the phenolic resin or poly(vinyl acetal) polymeric binder. The
useful nitrogen-containing organic compounds are "basic", meaning
that when added to water, it would form a solution having a pH
greater than 7. In some embodiments, they have a boiling point
greater than 300.degree. C. and an evaporation rate less than 0.01
relative to n-butyl acetate. In some embodiments, such compounds
also are liquids at room temperature (that is, about 25.degree.
C.).
DETAILED DESCRIPTION OF THE INVENTION
Definitions
[0023] Unless the context otherwise indicates, when used herein,
the terms "radiation-sensitive composition" and "imageable element"
are meant to be references to embodiments of the present
invention.
[0024] In addition, unless the context indicates otherwise, the
various components described herein such as "primary polymeric
binder", "phenolic resin", "poly(vinyl acetal)", "radiation
absorbing compound", and "basic nitrogen-containing organic
compound", also refer to mixtures of each component. Thus, the use
of the articles "a", "an", and "the" is not necessarily meant to
refer to only a single component.
[0025] Unless otherwise indicated, percentages refer to percents by
weight.
[0026] The term "single-layer imageable element" refers to an
imageable element having only one layer for imaging, but as pointed
out in more detail below, such elements may also include one or
more layers under or over (such as a topcoat) the imageable layer
to provide various properties.
[0027] As used herein, the term "radiation absorbing compound"
refers to compounds that are sensitive to certain wavelengths of
radiation and can convert photons into heat within the layer in
which they are disposed. These compounds may also be known as
"photothermal conversion materials", "sensitizers", or "light to
heat converters".
[0028] For clarification of definition of any terms relating to
polymers, reference should be made to "Glossary of Basic Terms in
Polymer Science" as published by the International Union of Pure
and Applied Chemistry ("IUPAC"), Pure Appl. Chem. 68, 2287-2311
(1996). However, any different definitions set forth herein should
be regarded as controlling.
[0029] The term "polymer" (for example, phenolic resin and
polyvinyl acetal) refers to high and low molecular weight polymers
including oligomers and includes both homopolymers and
copolymers.
[0030] The term "copolymer" refers to polymers that are derived
from two or more different monomers, or have two or more different
recurring units, even if derived from the same monomer.
[0031] The term "backbone" refers to the chain of atoms in a
polymer to which a plurality of pendant groups are attached. An
example of such a backbone is an "all carbon" backbone obtained
from the polymerization of one or more ethylenically unsaturated
polymerizable monomers. However, other backbones can include
heteroatoms wherein the polymer is formed by a condensation
reaction of some other means.
Uses
[0032] The radiation-sensitive compositions of this invention can
be used to form resist patterns in printed circuit board (PCB)
production, thick-and-thin film circuits, resistors, capacitors,
and inductors, multi-chip devices, integrated circuits, and active
semi-conductive devices. In addition, they can be used to provide
positive-working imageable elements that in turn can be used to
provide lithographic printing plates. Other uses would be readily
apparent to one skilled in the art.
Radiation-Sensitive Compositions
[0033] The radiation-sensitive compositions include one or more
aqueous alkaline solvent (developer) soluble polymeric binders as
the primary polymeric binders. These primary polymeric binders
include various phenolic resins and poly(vinyl acetals). The weight
average molecular weight (Mw) of the polymers useful as primary
binders is generally at least 5,000 and can be up to 300,000, and
typically it is from about 20,000 to about 50,000, as measured
using standard procedures. The optimal Mw may vary with the
specific class of polymer and its use.
[0034] The primary polymeric binders may be the only binders in the
radiation-sensitive composition (or imageable layer) but more
generally, they comprise at least 10 weight %, and more typically
at least 50 weight % and up to 90 weight %, based on the dry weight
of all polymeric binders. In some embodiments, the amount of
primary polymeric binders may be from about 55 to about 80 weight
%, based on the dry weight of all polymeric binders.
[0035] Some useful poly(vinyl acetals) are described for example,
in U.S. Pat. Nos. 6,255,033 and 6,541,181, and WO 2004/081662, all
noted above and incorporated herein by reference. The same or
similar poly(vinyl acetals) are described by Structures (I) and
(II) containing structural units (a) through (e) in EP 1,627,732
(Hatanaka et al.) and in US Published Patent Applications
2005/0214677 (Nagashima) and 2005/0214678 (Nagashima), all
incorporated herein by reference with respect to the poly(vinyl
acetals) described therein.
[0036] Structures (I) and (II) in EP 1,627,732 (noted above) are
not to be confused with Structures (I) and (II) defined below. Some
useful poly(vinyl acetals) comprise recurring units other than
acetal-containing recurring units as long as least 50 mol % (from
about 50 mol % to about 75 mol %, and more typically at least 60
mol %) of the recurring units are acetal-containing recurring
units. In such polymeric binders, the non-acetal-containing
recurring units may also have the same or different pendant
phenolic groups, or they may be recurring units having no pendant
phenolic groups, or they may comprise both types of recurring
units. For example, the poly(vinyl acetal) could also include
recurring units comprising an itaconic acid or crotonic acid group.
In addition, if there are recurring units comprising pendant
phenolic groups, those recurring units can have different pendant
phenolic groups [for example, a poly(vinyl acetal) could have
acetal-containing recurring units, and two or more different types
of recurring units with different pendant phenolic groups]. In
still other embodiments, a small molar amount (less than 20 mol %)
of the acetal groups in a poly(vinyl acetal) can be reacted with a
cyclic anhydride or isocyanate compound, such as toluene sulfonyl
isocyanate).
[0037] Useful poly(vinyl acetals) can also comprise recurring units
represented by the following Structure (PVAc):
##STR00001##
[0038] In Structure (PVAc), R and R' are independently hydrogen, or
a substituted or unsubstituted linear or branched alkyl group
having 1 to 6 carbon atoms (such as methyl, ethyl, n-propyl,
n-butyl, n-pentyl, n-hexyl, chloromethyl, trichloromethyl,
iso-propyl, iso-butyl, t-butyl, iso-pentyl, neo-pentyl,
1-methylbutyl and iso-hexyl groups), or substituted or
unsubstituted cycloalkyl ring having 3 to 6 carbon atoms in the
ring (such as cyclopropyl, cyclobutyl, cyclopentyl,
methylcyclohexyl, and cyclohexyl groups), or a halo group (such as
fluoro, chloro, bromo, or iodo). Typically, R and R' are
independently hydrogen, or a substituted or unsubstituted methyl or
chloro group, or for example, they are independently hydrogen or
unsubstituted methyl.
[0039] R.sup.2 is a substituted or unsubstituted phenol, a
substituted or unsubstituted naphthol, or a substituted or
unsubstituted anthracenol group. These phenol, naphthol and
anthracenol groups can have optionally up to 3 additional
substituents including additional hydroxy substituents, methoxy,
alkoxy, aryloxy, thioaryloxy, halomethyl, trihalomethyl, halo,
nitro, azo, thiohydroxy, thioalkoxy, cyano, amino, carboxy,
ethenyl, carboxyalkyl, phenyl, alkyl, alkenyl, alkynyl, cycloalkyl,
aryl, heteroaryl, and heteroalicyclic groups. For example, R.sup.2
can be an unsubstituted phenol or naphthol group such as a
2-hydroxyphenyl or a hydroxynaphthyl group.
[0040] Thus, the poly(vinyl acetals) can have a variety of other
recurring units besides those represented by Structure (PVAc), but
generally, at least 50 mol % of the recurring units are the same or
different recurring units represented by Structure (PVAc).
[0041] More specific useful poly(vinyl acetals) are represented by
the following Structure (I) comprising the noted recurring
units:
-(A).sub.m-(B).sub.n--(C).sub.p-(D).sub.q-(E).sub.r- (I)
wherein:
[0042] A represents recurring units represented by the following
Structure (Ia):
##STR00002##
[0043] B represents recurring units represented by the following
Structure (Ib):
##STR00003##
[0044] C represents recurring units represented by the following
Structure (Ic):
##STR00004##
[0045] D represents recurring units represented by the following
Structure (Id):
##STR00005##
[0046] E represents recurring units represented by the following
Structure (Ie):
##STR00006##
[0047] m is from about 5 to about 40 mol % (typically from about 15
to about 35 mol %), n is from about 10 to about 60 mol % (typically
from about 20 to about 40 mol %), p can be from 0 to about 20 mol %
(typically from 0 to about 10 mol %), q is from about 1 to about 20
mol % (typically from about 1 to about 15 mol %), and r is from
about 5 to about 60 mol % (typically from about 15 to about 55 mol
%).
[0048] R and R' are as described above for Structure (PVAc).
[0049] R.sup.1 is a substituted or unsubstituted, linear or
branched alkyl group having 1 to 12 carbon atoms (such as methyl,
ethyl, n-propyl, iso-propyl, t-butyl, n-butyl, n-pentyl, n-hexyl,
n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl,
methoxymethyl, chloromethyl, trichloromethyl, benzyl, cinnamoyl,
iso-propyl, iso-butyl, s-butyl, t-butyl, iso-pentyl, neo-pentyl,
1-methylbutyl, and iso-hexyl groups), substituted or unsubstituted
cycloalkyl ring having 3 to 6 carbon atoms in the ring (such as
cyclopropyl, cyclobutyl, cyclopentyl, methylcyclohexyl, and
cyclohexyl groups), or a substituted or unsubstituted aryl group
having 6 or 10 carbon atoms in the aromatic ring (such as
substituted or unsubstituted phenyl and naphthyl groups, including
phenyl, xylyl, tolulyl, p-methoxyphenyl, 3-chlorophenyl, and
naphthyl) other than a phenol or naphthol. Typically, R.sup.1 is a
substituted or unsubstituted alkyl group having 1 to 6 carbon atoms
such as n-propyl.
[0050] R.sup.2 is as defined above for Structure (PVAc).
[0051] R.sup.3 is a substituted or unsubstituted alkynyl group
having 2 to 4 carbon atoms (such as ethynyl groups), or a
substituted or unsubstituted phenyl group (such as phenyl,
4-carboxyphenyl, carboxyalkyleneoxyphenyl, and carboxyalkylphenyl
groups). Typically, R.sup.3 is a carboxyalkylphenyl group,
4-carboxyphenyl, or carboxyalkyleneoxyphenyl group, or another
carboxy-containing phenyl group.
[0052] R.sup.4 is an --O--C(.dbd.O)--R.sup.5 group wherein R.sup.5
is a substituted or unsubstituted alkyl group having 1 to 12 carbon
atoms or substituted or unsubstituted aryl group having 6 or 10
carbon atoms in the aromatic ring similarly to the definition of
R.sup.1 provided above. Typically, R.sup.5 is a substituted or
unsubstituted alkyl group having 1 to 6 carbon atoms such as an
unsubstituted methyl group.
[0053] R.sup.6 is a hydroxy group.
[0054] As indicated by the ratios of recurring units in Structure
(I), the poly(vinyl acetals) may be at least tetramers depending
upon the numbers of different recurring units present. For example,
there may be multiple different types of recurring units from any
of the defined classes of recurring units, of Structures (Ia)
through (Ie). For example, a poly(vinyl acetal) of Structure (I)
may have Structure (Ia) recurring units with different R.sup.1
groups. Such multiplicity of recurring units can also be true for
those represented by any of Structures (Ib) through (Ie).
[0055] A primary polymeric binder represented by Structure (I) may
contain recurring units other than those defined by Structures
(Ia), (Ib), (Ic), (Id), and (Ie), and such recurring units would be
readily apparent to a skilled worker in the art. Thus, Structure
(I) in its broadest sense is not limited to the defined recurring
units, but in some embodiments, only the recurring units in
Structure (I) are present.
[0056] Content of the primary polymeric binder in the
radiation-sensitive composition that forms a radiation-sensitive
layer is generally from about 10 to about 99% of the total dry
weight, and typically from about 30 to about 95% of the total dry
weight. Many embodiments would include the primary polymeric binder
in an amount of from about 50 to about 90% of the total composition
or layer dry weight.
[0057] The poly(vinyl acetals) described herein can be prepared
using known starting materials and reaction conditions including
those described in U.S. Pat. No. 6,541,181 (noted above).
[0058] For example, acetalization of the polyvinyl alcohols takes
place according to known standard methods for example as described
in U.S. Pat. Nos. 4,665,124 (Dhillon et al.), 4,940,646
(Pawlowski), 5,169,898 (Walls et al.), 5,700,619 (Dwars et al.),
and 5,792,823 (Kim et al.), and in Japanese Kokai 09-328,519
(Yoshinaga).
[0059] This acetalization reaction generally requires addition of a
strong inorganic or organic catalyst acid. Examples of catalyst
acids are hydrochloric acid, sulfuric acid, phosphoric acid, and
p-toluenesulfonic acid. Other strong acids are also useful such as
perfluoroalkylsulfonic acid and other perfluoro-activated acids.
The amount of acid should effectively allow protonation to occur,
but will not significantly alter the final product by causing
unwanted hydrolysis of the acetal groups. The reaction temperature
of the acetalization depends on the kind of aldehyde as well as the
desired level of substitution. It is between 0.degree. C. and, if
applicable, the boiling point of the solvent. Organic solvents as
well as mixtures of water with organic solvents are used for the
reaction. For example, suitable organic solvents are alcohols (such
as methanol, ethanol, propanol, butanol, and glycol ether), cyclic
ethers (such as 1,4-dioxane), and dipolar aprotic solvents (such as
N,N-dimethylformamid, N-methylpyrrolidone or dimethyl sulfoxide).
If acetalization is carried out in organic solvents or mixtures of
organic solvents with water, the reaction product often remains in
solution even if the starting polyvinyl alcohol was not completely
dissolved. Incomplete dissolution of the starting polyvinyl alcohol
in organic solvents is a disadvantage that may lead to
irreproducible degree of conversion and different products. Water
or mixtures of organic solvents with water should be used to
achieve complete dissolution of polyvinyl alcohol and reproducible
products as a result of acetalization. The sequence of the addition
of the various acetalization agents is often of no importance and
comparable finished products are obtained from different
preparation sequences. To isolate the finished products as a solid,
the polymer solution is introduced into a non-solvent under
vigorous stirring, filtered off and dried. Water is especially
suitable as a non-solvent for the polymers.
[0060] Unwanted hydrolysis of the acetal group achieved by
acetalization with hydroxyl-substituted aromatic aldehydes takes
place much easier than for the acetals built from aliphatic or not
substituted aromatic aldehydes or from aldehydes containing
carboxylic moieties at the same synthesis conditions. The presence
of even a small amount of water in the reaction mixture leads to
decreased degree of acetalization and incomplete conversion of the
aromatic hydroxy aldehyde used. On the other hand, it was found
that in the absence of water, the hydroxy-substituted aromatic
aldehydes react with hydroxyl groups of alcohols immediately and
with almost 100% conversion. So, the process of acetalization of
polyvinyl alcohols by hydroxy-substituted aromatic aldehydes to
achieve the desired polyvinyl acetals according can be carried out
different from the procedures known in the art. The water can be
removed from the reaction mixture during the synthesis by
distillation under reduced pressure and replaced with an organic
solvent. The remaining water may be removed by addition to the
mixture an organic material readily reactive with water and as a
result of the reaction producing volatile materials or inert
compounds. These materials may be chosen from carbonates,
orthoesters of carbonic or carboxylic acids, which easily react
with water, silica-containing compounds, such as diethylcarbonate,
trimethyl orthoformate, tetraethyl carbonate, and tetraethyl
silicate. The addition of these materials to reaction mixture leads
to 100% conversion of the used aldehydes.
[0061] Thus, the preparation of a useful poly(vinyl acetal) can
begin with dissolving of the starting polyvinyl alcohol in DMSO at
80-90.degree. C., then the solution is chilled to 60.degree. C.,
and the acidic catalyst dissolved in an organic solvent is added.
Then the solution of the aliphatic aldehyde in the same solvent is
added to the solution, the solution is kept for 30 minutes at
60.degree. C., and a solution of the aromatic aldehyde and/or
carboxylic substituted aldehyde, or other aldehyde in the same
solvent is added. Anisole is added to the reaction mixture, and the
azeothropic mixture of water with the anisole is removed by
distillation and is replaced by the organic solvent. At this stage,
the conversion of the aromatic hydroxy aldehyde reaches 95-98%. The
acid in the reaction mixture is neutralized and the mixture is
blended with water to precipitate the polymer that is filtrated,
washed with water, and dried. A second way to achieve 100% of
conversion of the aromatic hydroxyaldehyde to benzal is to add the
water removing organic material (for example, a carbonate or
orthoformate) after addition of the aldehydes to the reaction
mixture.
[0062] Various phenolic resins can also be used as primary
polymeric binders in this invention, including novolak resins such
as condensation polymers of phenol and formaldehyde, condensation
polymers of m-cresol and formaldehyde, condensation polymers of
p-cresol and formaldehyde, condensation polymers of m-/p-mixed
cresol and formaldehyde, condensation polymers of phenol, cresol
(m-, p-, or m-/p-mixture) and formaldehyde, and condensation
copolymers of pyrogallol and acetone. Further, copolymers obtained
by copolymerizing compound comprising phenol groups in the side
chains can be used. Mixtures of such polymeric binders can also be
used.
[0063] Novolak resins having a weight average molecular weight of
at least 1500 and a number average molecular weight of at least 300
are useful. Generally, the weight average molecular weight is in
the range of from about 3,000 to about 300,000, the number average
molecular weight is from about 500 to about 250,000, and the degree
of dispersion (weight average molecular weight/number average
molecular weight) is in the range of from about 1.1 to about
10.
[0064] Certain mixtures of the primary polymeric binders described
above can be used, including mixtures of one or more poly(vinyl
acetals) and one or more phenolic resins. For example, mixtures of
one or more poly(vinyl acetals) and one or more novolak or resol
(or resole) resins (or both novolak and resol resins) can be
used.
[0065] It may be useful to include a "secondary" polymeric binder
with the one or more primary polymeric binders described above. In
particular, such secondary polymeric binders may be useful in
combination with a poly(vinyl acetal) as described above.
[0066] The type of the secondary polymeric binder that can be used
together with the primary polymeric binder is not particularly
restricted. In general, from a viewpoint of not diminishing the
positive radiation-sensitivity of the imageable element, the
secondary polymeric binder is generally an alkali-soluble polymer
also.
[0067] Examples of secondary polymeric binders include the
following classes of polymers having an acidic group in (1) through
(5) shown below on a main chain and/or side chain (pendant
group).
[0068] (1) sulfone amide (--SO.sub.2NH--R),
[0069] (2) substituted sulfonamido based acid group (hereinafter,
referred to as active imido group) [such as --SO.sub.2NHCOR,
SO.sub.2NHSO.sub.2R, --CONHSO.sub.2R],
[0070] (3) carboxylic acid group (--CO.sub.2H),
[0071] (4) sulfonic acid group (--SO.sub.3H), and (5) phosphoric
acid group (--OPO.sub.3H.sub.2).
[0072] R in the above-mentioned groups (1)-(5) represents hydrogen
or a hydrocarbon group.
[0073] Representative secondary polymeric binders having the group
(1) sulfone amide group are for instance, polymers that are
constituted of a minimum constituent unit as a main component
derived from a compound having a sulfone amide group. Thus,
examples of such a compound include a compound having, in a
molecule thereof, at least one sulfone amide group in which at
least one hydrogen atom is bound to a nitrogen atom and at least
one polymerizable unsaturated group. Among these compounds are
m-aminosulfonylphenyl methacrylate,
N-(p-aminosulfonylphenyl)methacrylamide, and
N-(p-aminosulfonylphenyl)acrylamide. Thus, a homopolymer or a
copolymer of polymerizing monomers having a sulfoneamide group such
as m-aminosulfonylphenyl methacrylate, N-(p-aminosulfonylphenyl)
methacrylamide, or N-(p-aminosulfonylphenyl)acrylamide can be
used.
[0074] Examples of secondary polymeric binders with group (2)
activated imido group are polymers comprising recurring units
derived from compounds having activated imido group as the main
constituent component. Examples of such compounds include
polymerizable unsaturated compounds having a moiety defined by the
following structural formula.
##STR00007##
[0075] N-(p-toluenesulfonyl)methacrylamide and
N-(p-toluenesulfonyl) acrylamide are examples of such polymerizable
compounds.
[0076] Secondary polymeric binders having any of the groups (3)
through (5) include those readily prepared by reacting
ethylenically unsaturated polymerizable monomers having the desired
acidic groups, or groups that can be converted to such acidic
groups after polymerization.
[0077] Regarding the minimum constituent units having an acidic
group that is selected from the (1) through (5), there is no need
to use only one kind of acidic group in the polymer, and in some
embodiments, it may be useful to have at least two kinds of acidic
groups. Obviously, not every recurring unit in the secondary
polymeric binder must have one of the acidic groups, but usually at
least 10 mol % and typically at least 20 mol % comprise the
recurring units having one of the noted acidic groups.
[0078] The secondary polymeric binder can have a weight average
molecular weight of at least 2,000 and a number average molecular
weight of at least 500. Typically, the weight average molecular
weight is from about 5,000 to about 300,000, the number average
molecular weight is from about 800 to about 250,000, and the degree
of dispersion (weight average molecular weight/number average
molecular weight) is from about 1.1 to about 10.
[0079] Mixtures of the secondary polymeric binders may be used with
the one or more primary polymeric binders. The secondary polymeric
binder(s) can be present in an amount of at least 1 weigh % and up
to 50 weight %, and typically from about 5 to about 30 weight %,
based on the dry weight of the total polymeric binders in the
radiation-sensitive composition or imageable layer
[0080] The radiation-sensitive composition further comprises a
developability-enhancing composition that comprises one or more
basic nitrogen-containing organic compounds. In most embodiments,
each of these basic nitrogen-containing organic compounds has a
boiling point greater than 300.degree. C. and an evaporation rate
<0.01 relative to n-butyl acetate. Most of the useful basic
nitrogen-containing organic compounds are liquids at 25.degree. C.
Two or more of these compounds can be used in the same
developability-enhancing composition if desired.
[0081] Representative basic nitrogen-containing organic compounds
can be defined by the following structure (II):
(R.sup.7).sub.s--N--[(CR.sup.8R.sup.9).sub.t--OH].sub.v (II)
wherein t is 1 to 6, s is 0, 1, or 2, and v is 1 to 3, provided
that the sum of s and v is 3.
[0082] When s is 1, R.sup.7 is hydrogen, or a substituted or
unsubstituted, branched or linear alkyl, linear or branched
alkylamine group, cycloalkyl, heterocycloalkyl, carbocyclic aryl,
arylamine, or heteroaryl group. Such groups can be unsubstituted or
substituted with one or more of alkyl, haloalkyl, alkenyl, alkynyl,
cycloalkyl, aryl, heteroaryl, heteroalicyclic, halo, nitro, azo,
hydroxy, alkoxy, thiohydroxy, thioalkoxy, cyano, or amino
groups.
[0083] When s is 2, the multiple R.sup.7 groups can be the same or
different substituted or unsubstituted groups as defined for
R.sup.7 above when s is 1. Alternatively, the two R.sup.7 groups
can be taken together with the nitrogen atom to form a substituted
or unsubstituted heterocyclic ring. Substituents on this ring can
be, for example, one or more alkyl, hydroxylalkyl, haloalkyl,
alkenyl, alkynyl, cycloalkyl, aryl, arylamine, heteroaryl,
heteroalicyclic, halo, nitro, azo, hydroxy, alkoxy, thiohydroxy,
thioalkoxy, cyano and amino groups, which can be further
substituted, if desired with one or more halo, nitro, azo, hydroxy,
alkoxy, thiohydroxy, thioalkoxy, cyano or amino groups.
[0084] R.sup.8 and R.sup.9 can be the same or different hydrogen or
substituted or unsubstituted, linear or branched alkyl groups.
Representative substituents for the alkyl groups include one or
more alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, aryl,
heteroaryl, heteroalicyclic, halo, nitro, azo, hydroxy, alkoxy,
thiohydroxy, thioalkoxy, cyano and amino groups. Typically, t is 2
and R.sup.8 and R.sup.9 are both hydrogen.
[0085] Examples of basic nitrogen-containing organic compounds
useful in the developability-enhancing compositions are
N-(2-hydroxyethyl)-2-pyrrolidone, 1-(2-hydroxyethyl)piperazine,
N-phenyldiethanolamine, triethanolamine,
2-[bis(2-hydroxyethyl)amino]-2-hydroxymethyl-1.3-propanediol,
N,N,N',N'-tetrakis(2-hydroxyethyl)-ethylenediamine,
N,N,N',N'-tetrakis(2-hydroxypropyl)-ethylenediamine,
3-[(2-hydroxyethyl)phenylamino]propionitrile, and
hexahydro-1,3,5-tris(2-hydroxyethyl)-s-triazine. Mixtures of two or
more of these compounds are also useful. The basic
nitrogen-containing organic compounds can be obtained from a number
of commercial sources including BASF (Germany) and Aldrich Chemical
Company (Milwaukee, Wis.).
[0086] The basic nitrogen-containing organic compound(s) is present
in the radiation-sensitive composition (and imageable layer) in an
amount of from about 1 to about 30 weight %, and typically from
about 3 to about 15 weight %, based on the total solids of the
radiation-sensitive composition or total dry weight of the
imageable layer.
[0087] As noted above, these basic nitrogen-containing organic
compounds may be used alone, but they are also useful in any
combination of two or more.
[0088] It is also possible to use one or more of these basic
nitrogen-containing organic compounds in combination with one or
more acidic developability-enhancing compounds, such as carboxylic
acids or cyclic acid anhydrides, sulfonic acids, sulfinic acids,
alkylsulfuric acids, phosphonic acids, phosphinic acids, phosphonic
acid esters, phenols, sulfonamides, or sulfonimides, since such a
combination may permit further improved developing latitude and
printing durability. Representative examples of such compounds are
provided in [0030] to [0036] of U.S. Patent Application Publication
2005/0214677 (noted above) that is incorporated herein by reference
with respect to these acid developability-enhancing compounds. Such
compounds may be present in an amount of from about 0.1 to about 30
weight % based on the total dry weight of the radiation-sensitive
composition or imageable layer.
[0089] In some instances, at least two of these acidic
developability-enhancing compounds are used in combination with one
or more (such as two) of the basic-nitrogen-containing organic
compounds described above.
[0090] In the combination of basic and acidic compounds described
above, the molar ratio of one or more basic nitrogen-containing
organic compounds to one or more acidic developability-enhancing
compounds is generally from about 0.1:1 to about 10:1 and more
typically from about 0.5:1 to about 2:1.
[0091] The radiation-sensitive composition can include other
optional addenda as described below for the imageable layer.
Imageable Elements
[0092] The imageable elements are positive-working imageable
elements and the poly(vinyl acetals) or phenolic binders described
herein are generally present as polymeric binders in a single
imageable layer of these elements.
[0093] In general, the imageable elements are formed by suitable
application of a formulation of the radiation-sensitive composition
that contains one or more polymeric binders, the
developability-enhancing composition, and typically a radiation
absorbing compound (described below), as well as other optional
addenda, to a suitable substrate to form an imageable layer. This
substrate can be treated or coated in various ways as described
below prior to application of the formulation. For example, the
substrate can be treated to provide an "interlayer" for improved
adhesion or hydrophilicity, and the imageable layer is applied over
the interlayer.
[0094] The substrate generally has a hydrophilic surface, or a
surface that is more hydrophilic than the applied imaging
formulation on the imaging side. The substrate comprises a support
that can be composed of any material that is conventionally used to
prepare imageable elements such as lithographic printing plates. It
is usually in the form of a sheet, film, or foil, and is strong,
stable, and flexible and resistant to dimensional change under
conditions of use so that color records will register a full-color
image. Typically, the support can be any self-supporting material
including polymeric films (such as polyester, polyethylene,
polycarbonate, cellulose ester polymer, and polystyrene films),
glass, ceramics, metal sheets or foils, or stiff papers (including
resin-coated and metallized papers), or a lamination of any of
these materials (such as a lamination of an aluminum foil onto a
polyester film). Metal supports include sheets or foils of
aluminum, copper, zinc, titanium, and alloys thereof.
[0095] Polymeric film supports may be modified on one or both
surfaces with a "subbing" layer to enhance hydrophilicity, or paper
supports may be similarly coated to enhance planarity. Examples of
subbing layer materials include but are not limited to,
alkoxysilanes, amino-propyltriethoxysilanes,
glycidioxypropyl-triethoxysilanes, and epoxy functional polymers,
as well as conventional hydrophilic subbing materials used in
silver halide photographic films (such as gelatin and other
naturally occurring and synthetic hydrophilic colloids and vinyl
polymers including vinylidene chloride copolymers).
[0096] One substrate is composed of an aluminum support that may be
coated or treated using techniques known in the art, including
physical graining, electrochemical graining and chemical graining,
followed by anodizing. The aluminum sheet can be mechanically or
electrochemically grained and anodized using phosphoric acid or
sulfuric acid and conventional procedures.
[0097] An optional interlayer may be formed by treatment of the
aluminum support with, for example, a silicate, dextrine, calcium
zirconium fluoride, hexafluorosilicic acid, phosphate/sodium
fluoride, poly(vinyl phosphonic acid) (PVPA), vinyl phosphonic acid
copolymer, poly(acrylic acid), or acrylic acid copolymer solution.
The grained and anodized aluminum support can be treated with
poly(acrylic acid) using known procedures to improve surface
hydrophilicity.
[0098] The thickness of the substrate can be varied but should be
sufficient to sustain the wear from printing and thin enough to
wrap around a printing form. Some embodiments include a treated
aluminum foil having a thickness of from about 100 .mu.m to about
600 .mu.m.
[0099] The backside (non-imaging side) of the substrate may be
coated with antistatic agents and/or slipping layers or a matte
layer to improve handling and "feel" of the imageable element.
[0100] The substrate can also be a cylindrical surface having the
radiation-sensitive composition applied thereon, and thus be an
integral part of the printing press. The use of such imaged
cylinders is described for example in U.S. Pat. No. 5,713,287
(Gelbart).
[0101] The imageable layer typically comprises one or more
radiation absorbing compounds. While these compounds can be
sensitive to any suitable energy form (for example, UV, visible,
and IR radiation) from about 150 to about 1500 nm, they are
typically sensitive to infrared radiation and thus, the radiation
absorbing compounds are known as infrared radiation absorbing
compounds ("IR absorbing compounds") that generally absorb
radiation from about 600 to about 1400 nm and more likely, from
about 700 to about 1200 nm. The imageable layer is generally the
outermost layer in the imageable element.
[0102] Examples of suitable IR dyes include but are not limited to,
azo dyes, squarylium dyes, croconate dyes, triarylamine dyes,
thioazolium dyes, indolium dyes, oxonol dyes, oxazolium dyes,
cyanine dyes, merocyanine dyes, phthalocyanine dyes, indocyanine
dyes, indotricarbocyanine dyes, hemicyanine dyes, streptocyanine
dyes, oxatricarbocyanine dyes, thiocyanine dyes,
thiatricarbocyanine dyes, merocyanine dyes, cryptocyanine dyes,
naphthalocyanine dyes, polyaniline dyes, polypyrrole dyes,
polythiophene dyes, chalcogenopyryloarylidene and
bi(chalcogenopyrylo)-polymethine dyes, oxyindolizine dyes, pyrylium
dyes, pyrazoline azo dyes, oxazine dyes, naphthoquinone dyes,
anthraquinone dyes, quinoneimine dyes, methine dyes, arylmethine
dyes, polymethine dyes, squarine dyes, oxazole dyes, croconine
dyes, porphyrin dyes, and any substituted or ionic form of the
preceding dye classes. Suitable dyes are described for example, in
U.S. Pat. Nos. 4,973,572 (DeBoer), 5,208,135 (Patel et al.),
5,244,771 (Jandrue Sr. et al.), and 5,401,618 (Chapman et al.), and
EP 0 823 327A1 (Nagasaka et al.).
[0103] Cyanine dyes having an anionic chromophore are also useful.
For example, the cyanine dye may have a chromophore having two
heterocyclic groups. In another embodiment, the cyanine dye may
have at least two sulfonic acid groups, such as two sulfonic acid
groups and two indolenine groups. Useful IR-sensitive cyanine dyes
of this type are described for example in U.S. Patent Application
Publication 2005-0130059 (Tao).
[0104] A general description of a useful class of suitable cyanine
dyes is shown by the formula in [0026] of WO 2004/101280 (Munnelly
et al.).
[0105] In addition to low molecular weight IR-absorbing dyes, IR
dye moieties bonded to polymers can be used. Moreover, IR dye
cations can be used as well, that is, the cation is the IR
absorbing portion of the dye salt that ionically interacts with a
polymer comprising carboxy, sulfo, phospho, or phosphono groups in
the side chains.
[0106] Near infrared absorbing cyanine dyes are also useful and are
described for example in U.S. Pat. Nos. 6,309,792 (Hauck et al.),
6,264,920 (Achilefu et al.), 6,153,356 (Urano et al.), 5,496,903
(Watanate et al.). Suitable dyes may be formed using conventional
methods and starting materials or obtained from various commercial
sources including American Dye Source (Baie D'Urfe, Quebec, Canada)
and FEW Chemicals (Germany). Other useful dyes for near infrared
diode laser beams are described, for example, in U.S. Pat. No.
4,973,572 (noted above). The following IR dyes are representative
of useful radiation absorbing compounds and are not meant to be
limiting in any way:
##STR00008##
[0107] Same as above but with C.sub.3F.sub.7CO.sub.2-- as the
anion.
##STR00009## ##STR00010##
[0108] Useful IR absorbing compounds can also be pigments including
carbon blacks such as carbon blacks that are surface-functionalized
with solubilizing groups are well known in the art. Carbon blacks
that are grafted to hydrophilic, nonionic polymers, such as
FX-GE-003 (manufactured by Nippon Shokubai), or which are
surface-functionalized with anionic groups, such as CAB-O-JET.RTM.
200 or CAB-O-JET.RTM. 300 (manufactured by the Cabot Corporation)
are also useful. Other useful pigments include, but are not limited
to, Heliogen Green, Nigrosine Base, iron (III) oxides, manganese
oxide, Prussian Blue, and Paris Blue. The size of the pigment
particles should not be more than the thickness of the imageable
layer and preferably the pigment particle size will be less than
half the thickness of the imageable layer.
[0109] In the imageable elements, the radiation absorbing compound
is generally present at a dry coverage of from about 0.1 to about
20 weight %, or it is an IR dye that is present in an amount of
from about 0.5 to about 5 weight %. Alternatively, the amount can
be defined by an absorbance in the range of from about 0.05 to
about 3, or from about 0.1 to about 1.5, in the dry film as
measured by reflectance UV-visible spectrophotometry. The
particular amount needed for this purpose would be readily apparent
to one skilled in the art, depending upon the specific compound
used.
[0110] Alternatively, the radiation absorbing compounds may be
included in a separate layer that is in thermal contact with the
single imageable layer. Thus, during imaging, the action of the
radiation absorbing compound in the separate layer can be
transferred to the imageable layer without the compound originally
being incorporated into it.
[0111] The imageable layer (and radiation-sensitive composition)
can also include one or more additional compounds that act as
colorant dyes. Colorant dyes that are soluble in an alkaline
developer are useful. Useful polar groups for colorant dyes include
but are not limited to, ether groups, amine groups, azo groups,
nitro groups, ferrocenium groups, sulfoxide groups, sulfone groups,
diazo groups, diazonium groups, keto groups, sulfonic acid ester
groups, phosphate ester groups, triarylmethane groups, onium groups
(such as sulfonium, iodonium, and phosphonium groups), groups in
which a nitrogen atom is incorporated into a heterocyclic ring, and
groups that contain a positively charged atom (such as quaternized
ammonium group). Compounds that contain a positively-charged
nitrogen atom useful as dissolution inhibitors include, for
example, tetralkyl ammonium compounds and quaternized heterocyclic
compounds such as quinolinium compounds, benzothiazolium compounds,
pyridinium compounds, and imidazolium compounds. Useful colorant
dyes include triarylmethane dyes such as ethyl violet, crystal
violet, malachite green, brilliant green, Victoria blue B, Victoria
blue R, and Victoria pure blue BO, BASONYL.RTM. Violet 610 and D11
(PCAS, Longjumeau, France). These compounds can act as contrast
dyes that distinguish the non-exposed (non-imaged) regions from the
exposed (imaged) areas in the developed imageable element.
[0112] When a colorant dye is present in the imageable layer, its
amount can vary widely, but generally it is present in an amount of
from about 0.5 weight % to about 30 weight % (based on the total
dry layer weight).
[0113] The imageable layer (and radiation-sensitive composition)
can further include a variety of other additives including
dispersing agents, humectants, biocides, plasticizers, nonionic or
amphoteric surfactants for coatability or other properties (such as
fluoropolymers), wear-resistant polymers (such as polyurethanes,
polyesters, epoxy resins, polyamides, and acrylic resins),
viscosity builders, fillers and extenders, dyes or colorants to
allow visualization of the written image, pH adjusters, drying
agents, defoamers, preservatives, antioxidants, development aids,
rheology modifiers or combinations thereof, or any other addenda
commonly used in the lithographic art, in conventional amounts (for
example, as described in US Patent Application Publication
2005/0214677, noted above).
[0114] The positive-working imageable element can be prepared by
applying the imageable layer formulation over the surface of the
substrate (and any other hydrophilic layers provided thereon) using
conventional coating or lamination methods. Thus, the formulation
can be applied by dispersing or dissolving the desired ingredients
in a suitable coating solvent, and the resulting formulation is
applied to the substrate using suitable equipment and procedures,
such as spin coating, knife coating, gravure coating, die coating,
slot coating, bar coating, wire rod coating, roller coating, or
extrusion hopper coating. The formulation can also be applied by
spraying onto a suitable support (such as an on-press printing
cylinder).
[0115] The coating weight for the single imageable layer is from
about 0.5 to about 2.5 g/m.sup.2 or from about 1 to about 2
g/m.sup.2.
[0116] The selection of solvents used to coat the layer
formulation(s) depends upon the nature of the polymeric binders and
other polymeric materials and non-polymeric components in the
formulations. Generally, the imageable layer formulation is coated
out of acetone, methyl ethyl ketone, or another ketone,
tetrahydrofuran, 1-methoxy propan-2-ol (or 1-methoxy-2-propanol),
N-methyl pyrrolidone, 1-methoxy-2-propyl acetate,
.gamma.-butyrolactone, and mixtures thereof using conditions and
techniques well known in the art.
[0117] Alternatively, the layer(s) may be applied by conventional
extrusion coating methods from melt mixtures of the respective
layer compositions. Typically, such melt mixtures contain no
volatile organic solvents.
[0118] Intermediate drying steps may be used between applications
of the various layer formulations to remove solvent(s) before
coating other formulations. Drying steps may also help in
preventing the mixing of the various layers.
[0119] A representative method for preparing positive-working
single-layer imageable elements is described below in the
examples.
[0120] After the imageable layer formulation is dried on the
substrate (that is, the coating is self-supporting and dry to the
touch), the element can be heat treated at from about 40 to about
90.degree. C. (typically at from about 50 to about 70.degree. C.)
for at least 4 hours and typically at least 20 hours, or for at
least 24 hours. The maximum heat treatment time can be as high as
96 hours, but the optimal time and temperature for the heat
treatment can be readily determined by routine experimentation.
Such heat treatments are described for example, in EP 823,327
(Nagasaka et al.) and EP 1,024,958 (McCullough et al.).
[0121] It may also be desirable that during the heat treatment, the
imageable element is wrapped or encased in a water-impermeable
sheet material to represent an effective barrier to moisture
removal from the precursor. This sheet material can be sufficiently
flexible to conform closely to the shape of the imageable element
(or stack thereof) and is generally in close contact with the
imageable element (or stack thereof). For example, the
water-impermeable sheet material is sealed around the edges of the
imageable element or stack thereof. Such water-impermeable sheet
materials include polymeric films or metal foils that are sealed
around the edges of imageable element or stack thereof.
[0122] Alternatively, heat treatment of the imageable element (or
stack thereof) can be carried out in an environment in which
relative humidity is controlled to from about 25% or from about
30%. Relative humidity is defined as the amount of water vapor
present in air expressed as a percentage of the amount of water
required for saturation at a given temperature.
[0123] Usually, at least 5 and up to 100 of the imageable elements
are heat treated at the same time. More commonly, such a stack
includes at least 500 imageable elements.
[0124] It may be difficult to achieve good wrapping at the top and
bottom of such a stack using the water-impermeable sheet material
and in such instances, it may be desirable to use "dummy" or reject
elements in those regions of the stack. Thus, the heat-treated
stack may include at least 100 useful imageable elements in
combination with dummy or reject elements. These dummy or reject
elements also serve to protect the useful elements from damage
caused by the wrapping or sealing process.
[0125] Alternatively, the imageable element(s) may be heat treated
in the form of a coil and then cut into individual elements at a
later time. Such coils can include at least 1000 m.sup.2 of
imageable surface and more typically at least 3000 m.sup.2 of
imageable surface.
[0126] Adjacent coils or "spirals" or a coil, or strata of a stack
may, if desired, be separated by interleaving materials, for
example, papers or tissues that may be sized with plastics or
resins (such as polythene).
Imaging and Development
[0127] The imageable elements of this invention can have any useful
form including, but not limited to, printing plate precursors,
printing cylinders, printing sleeves and printing tapes (including
flexible printing webs). For example, the imageable members are
lithographic printing plate precursors for forming lithographic
printing plates.
[0128] Printing plate precursors can be of any useful size and
shape (for example, square or rectangular) having the requisite
imageable layer disposed on a suitable substrate. Printing
cylinders and sleeves are known as rotary printing members having
the substrate and imageable layer in a cylindrical form. Hollow or
solid metal cores can be used as substrates for printing
sleeves.
[0129] During use, the imageable elements are exposed to a suitable
source of radiation such as UV, visible light, or infrared
radiation, depending upon the radiation absorbing compound present
in the radiation-sensitive composition, at a wavelength of from
about 150 to about 1500 nm. For most embodiments, imaging is
carried out using an infrared laser at a wavelength of from about
700 to about 1200 nm. The laser used to expose the imaging member
can be a diode laser, because of the reliability and low
maintenance of diode laser systems, but other lasers such as gas or
solid-state lasers may also be used. The combination of power,
intensity and exposure time for laser imaging would be readily
apparent to one skilled in the art. Presently, high performance
lasers or laser diodes used in commercially available imagesetters
emit infrared radiation at a wavelength of from about 800 to about
850 nm or from about 1060 to about 1120 nm.
[0130] The imaging apparatus can function solely as a platesetter
or it can be incorporated directly into a lithographic printing
press. In the latter case, printing may commence immediately after
imaging, thereby reducing press set-up time considerably. The
imaging apparatus can be configured as a flatbed recorder or as a
drum recorder, with the imageable member mounted to the interior or
exterior cylindrical surface of the drum. A useful imaging
apparatus is available as models of Creo Trendsetter.RTM.
imagesetters available from Eastman Kodak Company (Burnaby, British
Columbia, Canada) that contain laser diodes that emit near infrared
radiation at a wavelength of about 830 nm. Other suitable imaging
sources include the Crescent 42T Platesetter that operates at a
wavelength of 1064 nm (available from Gerber Scientific, Chicago,
Ill.) and the Screen PlateRite 4300 series or 8600 series
platesetter (available from Screen, Chicago, Ill.). Additional
useful sources of radiation include direct imaging presses that can
be used to image an element while it is attached to the printing
plate cylinder. An example of a suitable direct imaging printing
press includes the Heidelberg SM74-DI press (available from
Heidelberg, Dayton, Ohio).
[0131] IR imaging speeds may be from about 30 to about 1500
mJ/cm.sup.2, or from about 40 to about 200 mJ/cm.sup.2.
[0132] While laser imaging is usually practiced, imaging can be
provided by any other means that provides thermal energy in an
imagewise fashion. For example, imaging can be accomplished using a
thermoresistive head (thermal printing head) in what is known as
"thermal printing", described for example in U.S. Pat. No.
5,488,025 (Martin et al.). Thermal print heads are commercially
available (for example, as Fujitsu Thermal Head FTP-040 MCS001 and
TDK Thermal Head F415 HH7-1089).
[0133] Imaging is generally carried out using direct digital
imaging. The image signals are stored as a bitmap data file on a
computer. Such data files may be generated by a raster image
processor (RIP) or other suitable means. The bitmaps are
constructed to define the hue of the color as well as screen
frequencies and angles.
[0134] Imaging of the imageable element produces an imaged element
that comprises a latent image of imaged (exposed) and non-imaged
(non-exposed) regions. Developing the imaged element with a
suitable developer removes the exposed regions of the imageable
layer and any layers underneath it, and exposing the hydrophilic
surface of the substrate. Thus, such imageable elements are
"positive-working" (for example, "positive-working" lithographic
printing plate precursors).
[0135] Thus, development is carried out for a time sufficient to
remove the imaged (exposed) regions of the imageable layer, but not
long enough to remove the non-imaged (non-exposed) regions of the
imageable layer. The imaged (exposed) regions of the imageable
layer are described as being "soluble" or "removable" in the
developer because they are removed, dissolved, or dispersed within
the developer more readily than the non-imaged (non-exposed)
regions of the imageable layer. The term "soluble" also means
"dispersible".
[0136] The imaged elements are generally developed using
conventional processing conditions. Both aqueous alkaline
developers and organic solvent-containing developers can be used.
In most embodiments of the method of this invention, the higher pH
aqueous alkaline developers are used.
[0137] Aqueous alkaline developers generally have a pH of at least
7 and typically of at least 11. Useful alkaline aqueous developers
include 3000 Developer, 9000 Developer, GOLDSTAR Developer,
GOLDSTAR Plus Developer, GOLDSTAR Premium Developer, GREENSTAR
Developer, ThermalPro Developer, PROTHERM Developer, MX1813
Developer, and MX1710 Developer (all available from Eastman Kodak
Company, Norwalk, Conn.), and the "L-6" Developer (described below
before the Examples). These compositions also generally include
surfactants, chelating agents (such as salts of
ethylenediaminetetraacetic acid), and alkaline components (such as
inorganic metasilicates, organic metasilicates, hydroxides, and
bicarbonates).
[0138] Organic solvent-containing developers are generally
single-phase solutions of one or more organic solvents that are
miscible with water. Useful organic solvents the reaction products
of phenol with ethylene oxide and propylene oxide [such as ethylene
glycol phenyl ether (phenoxyethanol)], benzyl alcohol, esters of
ethylene glycol and of propylene glycol with acids having 6 or less
carbon atoms, and ethers of ethylene glycol, diethylene glycol, and
of propylene glycol with alkyl groups having 6 or less carbon
atoms, such as 2-ethylethanol and 2-butoxyethanol. The organic
solvent(s) is generally present in an amount of from about 0.5 to
about 15% based on total developer weight. Such developers can be
neutral, alkaline, or slightly acidic in pH. Most of these
developers are alkaline in pH, for example up to pH 11.
[0139] Representative organic solvent-containing developers include
ND-1 Developer, "2 in 1" Developer, 955 Developer, and 956
Developer (all available from Eastman Kodak Company, Norwalk,
Conn.).
[0140] Generally, the developer is applied to the imaged element by
rubbing or wiping it with an applicator containing the developer.
Alternatively, the imaged element can be brushed with the developer
or the developer may be applied by spraying the element with
sufficient force to remove the exposed regions. Still again, the
imaged element can be immersed in the developer. In all instances,
a developed image is produced in a lithographic printing plate
having excellent resistance to press room chemicals.
[0141] Following development, the imaged element can be rinsed with
water and dried in a suitable fashion. The dried element can also
be treated with a conventional gumming solution (preferably gum
arabic).
[0142] The imaged and developed element can also be baked in a
post-exposure bake operation that can be carried out to increase
run length of the resulting imaged element. Baking can be carried
out, for example at from about 220.degree. C. to about 240.degree.
C. for from about 2 to about 10 minutes, or at about 120.degree. C.
for 30 minutes.
[0143] Printing can be carried out by applying a lithographic ink
and fountain solution to the printing surface of the imaged
element. The ink is taken up by the non-imaged (non-exposed or
non-removed) regions of the imageable layer and the fountain
solution is taken up by the hydrophilic surface of the substrate
revealed by the imaging and development process. The ink is then
transferred to a suitable receiving material (such as cloth, paper,
metal, glass, or plastic) to provide a desired impression of the
image thereon. If desired, an intermediate "blanket" roller can be
used to transfer the ink from the imaged member to the receiving
material. The imaged members can be cleaned between impressions, if
desired, using conventional cleaning means and chemicals.
[0144] The following examples are presented as a means to
illustrate the practice of this invention but the invention is not
intended to be limited thereby.
EXAMPLES
[0145] The following components were used in the preparation and
use of the examples. Unless otherwise indicated, the components are
available from Aldrich Chemical Company (Milwaukee, Wis.):
[0146] BF-03 represents a poly(vinyl alcohol), 98% hydrolyzed
(Mw=15,000) that was obtained from Chang Chun Petrochemical Co.
Ltd. (Taiwan).
[0147] BIS-TRIS represents
2,2-bis(hydroxymethyl)-2,2',2''-nitrilotriethanol.
[0148] Byk.RTM. 307 is a 25% (weight) solution of a modified
dimethyl polysiloxane copolymer in xylene/methoxypropyl acetate
that was obtained from BYK Chemie (Wallingford, Conn.).
[0149] Crystal Violet (C.I. 42555) is Basic Violet 3
(.lamda..sub.max=588 nm).
[0150] DMSO represents dimethylsulfoxide.
[0151] HEP represents 1-(2-hydroxyethyl)-2-pyrrolidone.
[0152] HEPAPN represents
3-[(2-hydroxyethyl)phenylamino]-propionitrile.
[0153] L-6 represents a potassium silicate aqueous developer
containing sodium salicylate (1%), D-sorbitol (1%), Triton.RTM. H55
nonionic surfactant (0.5%), Tergitol.RTM. NP12 surfactant (0.04%),
potassium silicate (8.2%) and water, and has a K.sub.2O:SiO.sub.2
molar ratio of about 1:1.2 and a pH of about 13.5. The percentages
are by weight.
[0154] MEK represents methyl ethyl ketone.
[0155] MSA represents methanesulfonic acid (99%).
[0156] NMP represents N-methylpyrrolidone.
[0157] PDEA represents N-phenyldiethanolamine
[0158] PG represents phloroglucinol.
[0159] PM represents 1-methoxy-2-propanol (also known as Dowanol
PM).
[0160] Ruthapen LB 9900 is a cresol resol resin that was obtained
from Hexion AG (Germany).
[0161] Ruthapen 0744 LB is a cresol novolak resin that was obtained
from Bakelight AG (Germany).
[0162] S 0451 is an IR dye (.lamda..sub.max=775 nm) that was
obtained from FEW Chemicals (Germany).
[0163] S 0094 is an IR dye (.lamda..sub.max=813 nm) that was
obtained from FEW Chemicals (Germany).
[0164] Sudan Black B is a neutral diazo dye (C.U. 26150).
[0165] TEA represents triethanolamine.
[0166] TETRAKIS-HEEDA represents
N,N,N',N'-tetrakis(2-hydroxyethyl)-ethylenediamine.
[0167] TETRAKIS-HPEDA represents
N,N,N',N'-tetrakis(2-hydroxypropyl)-ethylenediamine.
[0168] THPE represents 1,1,1-tris(4-hydroxyphenyl)ethane.
[0169] Victoria Blue R is a triarylmethane dye (C.I. 44040).
[0170] Polymer A (as defined by Structure I above) was prepared
using the following procedure:
[0171] BF-03 (50 g) was added to reaction vessel fitted with a
water-cooled condenser, a dropping funnel, and thermometer, and
containing DMSO (200 g). With continual stirring, the mixture was
heated for 30 minutes at 80.degree. C. until it became a clear
solution. The temperature was then adjusted at 60.degree. C. and
MSA (2.7 g) in DMSO (50 g) was added. Over 15 minutes, a solution
of butyraldehyde (10.4 g) was added to the reaction mixture and it
was kept for 1 hour at 55-60.degree. C. Then, 2-hydroxybenzaldehyde
(salicylic aldehyde, 39 g) in DMSO (100 g) was added to the
reaction mixture. The reaction mixture was then diluted with
anisole (350 g) and vacuum distillation was started. The
anisole:water azeotrope was distilled out from the reaction mixture
(less than 0.1% of water remained in the solution). The reaction
mixture was chilled to room temperature and was neutralized with
TEA (8 g) dissolved in DMSO (30 g), then blended with 6 kg of
water. The resulting precipitated polymer was washed with water,
filtered, and dried in vacuum for 24 hours at 50.degree. C. to
obtain 86 g of dry Polymer A.
Invention Examples 1-4 and Comparative Examples 1 & 2
[0172] Imageable elements of the present invention and two
Comparative elements outside of this invention (Comparative Example
1 being a "Control") were prepared in the following manner with the
radiation-sensitive compositions having the following
components:
TABLE-US-00001 Ruthaphen 744 LB 7.22 g Crystal Violet 0.2 g S 0094
IR Dye 0.16 g Basic nitrogen-containing organic compound 0.4 g
total (see TABLE I below) PM 91.8 g
[0173] Each formulation was filtered and applied to an
electrochemically roughened and anodized aluminum substrate that
had been subjected to a treatment with an aqueous solution of
poly(vinyl phosphonic acid) by means of common methods and the
resulting imageable layer coating was dried for 2.5 minutes at
105.degree. C. in Glunz&Jensen "Unigraph Quartz" oven. The dry
coverage of each imageable layer was about 1.5 g/m.sup.2.
[0174] Each resulting imageable element was exposed on a CREO.RTM.
Lotem 400 Quantum imager in a range of energies of 40 mJ/cm.sup.2
to 200 mJ/cm.sup.2 and developed for 30 seconds at 25.degree. C. in
a Glunz&Jensen "InterPlater 85HD" processor using the GOLDTAR
Premium Developer. The resulting printing plates were evaluated for
sensitivity (clearing point: the lowest imaging energy at which the
exposed regions were completely removed by the developer at a given
temperature and time) and Cyan density loss in the non-exposed
areas. The results are shown in TABLE I.
TABLE-US-00002 TABLE I Acidic Developability- Basic Nitrogen-
Boiling Point of Basic Enhancing containing Organic
Nitrogen-containing Sensitivity mJ/cm.sup.2 Cyan Density Element
Compound (g) Compound Organic Compound (23.degree. C./30 sec.) Loss
(%) Comparative 1 0 0 -- 160* 5.7 Comparative 2 THPE 0 m.p.
55.degree. C. 90 4.7 Invention Example 1 0 HEP >319 80 4.8
Invention Example 2 0 BIS-TRIS m.p. 104.degree. C. 80 5.5 Invention
Example 3 THPE** BIS-TRIS Not available 80 6.5 Invention Example 4
THPE*** HEP Not available 80 6.2 *Element developed at 25.degree.
C./40 seconds. **BIS-TRIS:THPE used at weight ratio of 1:1
***HEP:THPE used at weight ratio of 1:1
[0175] The results in TABLE I show that addition of a basic
nitrogen-containing organic compound as a developability enhancing
compound according to the present invention (Invention Examples 1
and 2) to a novolak-containing radiation-sensitive compositions and
imageable layers provided printing plate precursors having high
sensitivity when imaged in digital imaging device at 700-1000 nm.
In addition, when the elements of this invention were developed in
an aqueous alkaline developer, there was acceptable low weight loss
in the non-exposed regions.
[0176] Moreover, the results in Invention Examples 3 and 4 show
that the use of these basic nitrogen-containing organic compounds
in combination with an acidic developability-enhancing compound
(for example, THPE) in the radiation-sensitive composition and
imageable layer provided imageable elements with high sensitivity
when imaged in digital imaging device at 700-1000 nm. In addition,
when the elements of this invention were developed in an aqueous
alkaline developer, there was acceptable low weight loss in the
non-exposed regions.
Invention Examples 5-11 and Comparative Example 3
[0177] Imageable elements of the present invention and a
Comparative element outside of this invention were prepared in the
following manner with the radiation-sensitive compositions having
the following components:
TABLE-US-00003 Polymer A 16.3 g Victoria Blue R 0.34 g S 0094 IR
Dye 0.48 g Basic nitrogen-containing organic compound 1.6 g (see
TABLE II below) PM 162.9 g
[0178] Each formulation was filtered and applied to an
electrochemically roughened and anodized aluminum substrate that
had been subjected to a treatment with an aqueous solution of
poly(vinyl phosphonic acid) by means of common methods and the
resulting imageable layer coating was dried for 2.5 minutes at
100.degree. C. in Glunz&Jensen "Unigraph Quartz" oven. The dry
coverage of each imageable layer was about 1.5 g/m.sup.2.
[0179] Each resulting imageable element was exposed on a CREO.RTM.
Lotem 400 Quantum imager in a range of energies of 40 mJ/cm.sup.2
to 350 mJ/cm.sup.2 and developed for 30 seconds at 25.degree. C. in
a Glunz&Jensen "InterPlater 85HD" processor using the L-6 (90
ms) developer. The resulting printing plates were evaluated for
sensitivity (clearing point: the lowest imaging energy at which the
exposed regions were completely removed by the developer at a given
temperature and time) and Cyan density loss in the non-exposed
areas. The results are shown in TABLE II.
TABLE-US-00004 TABLE II Basic nitrogen- Sensitivity containing
Boiling mJ/cm.sup.2 Cyan organic point (25.degree. C./ Density
Element compound (.degree. C.) 30 sec.) Loss (%) Comparative 3 None
-- 350 3.3 Invention HEP 305 70 6.6 Example 5 Invention TEA >319
80 5.1 Example 6 (23.degree. C./ 20 sec.) Invention HEPAPN 315 130
2.7 Example 7 Invention PDEA m.p. 55.degree. C. 70 3.9 Example 8
Invention BIS-TRIS m.p. 104.degree. C. 80 5.3 Example 9 Invention
TETRAKIS- >320 80 6.2 Example 10 HEEDA Invention TETRAKIS- b.p.
190.degree. C. 90 4.6 Example 11 HPEDA (1 mmHg)
[0180] The results in TABLE II show that the addition of basic
nitrogen-containing organic compounds as developability enhancing
compounds according to this invention to radiation-sensitive
compositions and imageable layers containing a poly(vinyl acetal)
provided imageable elements with high sensitivity when imaged in
digital imaging device at 700-1000 nm. In addition, when the imaged
elements of this invention were developed in an aqueous alkaline
developer, there was acceptable low weight loss in the non-exposed
regions.
Invention Examples 12-19 & Comparative Examples 4 & 5
[0181] Imageable elements of the present invention and Comparative
elements outside of this invention were prepared in the following
manner with the radiation-sensitive compositions having the
following components:
TABLE-US-00005 Polymer A 11 g Crystal Violet 0.42 g S 0094 IR Dye
0.17 g S 0451 IR Dye 0.29 g Ruthaphen LB 9900 5.0 g Sudan Black B
0.17 g Basic nitrogen organic compound (see TABLE III below with
amounts) PM 120 g MEK 15 g
[0182] Each formulation was filtered and applied to an
electrochemically roughened and anodized aluminum substrate that
had been subjected to a treatment with an aqueous solution of
poly(vinyl phosphonic acid) by means of common methods and the
resulting imageable layer coating was dried for 1 minute at
100.degree. C. in Glunz&Jensen "Unigraph Quartz" oven. After
the imageable layers were coated, they were heat treated at a
temperature of 55.degree. C. and a relative humidity of 25% RH for
3 days. The dry coverage of each imageable layer was about 1.5
g/m.sup.2.
[0183] Each resulting imageable element was exposed on a CREO.RTM.
Lotem 400 Quantum imager in a range of energies 40 mJ/cm.sup.2 to
150 mJ/cm.sup.2 and developed for 30 seconds at 23.degree. C. in a
Glunz&Jensen "InterPlater 85HD" processor using the using the
L-6 (90 ms) developer. The resulting printing plates were evaluated
for sensitivity (clearing point: the lowest imaging energy at which
the exposed regions were completely removed by the developer at a
given temperature and time) and Cyan Density Loss in the
non-exposed areas.
[0184] Thereafter, each of the printing plates was mounted on a
Heidelberg GTO-52 press to print 200K impressions. The dot % for
1%, 2%, 3%, 5% and 50% dots were measured on the prints every 10K
impressions and the plates were judged as excellent if the dot %
for the 1% dots was sharpened less than 10%. The results are shown
in the following TABLE III.
TABLE-US-00006 TABLE III Acidic Developability- Sensitivity
Enhancing Compound Basic Nitrogen-containing mJ/cm.sup.2 Cyan
Density Press performance Element (g) Organic Compound (23.degree.
C./30 sec.) Loss (%) (1000 .times. copies)* Comparative 4 0 0
>>150 2.3 >200 Comparative 5 PG (1.05 g) 0 50 6.7 >200
Invention Example 12 PG (0.5 g) HEP (0.5 g) 40 9.8 >200
Invention Example 13 THPE (1.0 g) HEP (0.5 g) 50 4.5 >200
Invention Example 14 0 HEP (1.5 g) 40 8.6 >200 Invention Example
15 0 HEP (0.5 g) + TETRAKIS- 60 5.2 >200 HPEDA (0.5 g) Invention
Example 16 0 Bis-Tris (1.05 g) 50 6.2 200 Invention Example 17 0
TETRAKIS-HPEDA (1.5 g) 60 4.9 >200 Invention Example 18 0
TETRAKIS-HPEDA (0.5 g) + 50 5.8 >200 Bis-Tris (0.5 g) Invention
Example 19 0 HEP (0.5 g) + Bis-Tris (0.5 g) 50 5.4 >200 *1% dots
changed less than 10%.
[0185] The results in TABLE III show that using one or more basic
nitrogen-containing organic compounds as developability enhancing
compounds according to the present invention in radiation-sensitive
compositions and imageable layers containing a poly(vinyl acetal)
provided printing plate precursors (imageable elements) having high
sensitivity when imaged in digital imaging device at 700-1000 nm.
Moreover, upon development, they showed acceptable low weight
losses in the not-exposed regions, and provided extremely good
durable printing performance.
[0186] The results in Invention Examples 12 and 13 also show that
the use of at least one of these basic nitrogen-containing organic
compounds in combination with an acidic developability-enhancing
compound provided improved developing latitude and printing.
[0187] The invention has been described in detail with particular
reference to certain preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *